In learning mathematics, students often experience mistakes or omissions in solving the questions given both the questions of practice, assignments, tests, and exams. This study aims to determine the student's errors mistakes in solving mathematical problems in the composition and inverse functions in SMA Negeri 1 Maumere. The method used is descriptive qualitative, with X MIPA 4 students' research subjects, amounting to 34 people who were selected based on purposive sampling technique where this subject who gets material on compulsory mathematics, namely the material composition function and inverse function. Data collection procedures are taken through the provision of test questions and interviews whit students. Data analysis includes data reduction, data presentation, and conclusions. This study results can be said that the student's errors in solving mathematical problems in the composition and inverse functions of high, medium, and low ability students make the same mistakes, namely errors in using data, language interpretation errors, and technical errors.

Teaching aids in the world of education is a medium that mediates to help clarifying concepts in learning mathematics. This study aims to determine the efect of the use of toy car props on students’ interest in learning mathematics, especially in comparison material. This research was conducted at SMPN I Bola VII class semester 2 of the 2019/2020 scholl year. This type of research is quantitative by using a quasi-experimental methods. The population of this study were 192 studentsof class VII SMPN I Bola with a sample 0f 23 students in the experimental class and 23 from the control class. The sampling technique used is class random technique. The instrument used in this study was a questionnaire of interest in learning. Before carrying out a hypothesis test it is necessary to do a prerequisite test that is a test for normality and homogeneit. The normality test  obtained significant values in the experimental class and control were 0,136 and 0,620, because the value obtained has a significance level 0f >0,05, it can be stated that the data is normally distributed. For the homogeneity test, the results obtained a significant value of 0,001 at a sisnificant level of 0,05, so it can be said that the data is homogeneous. After the data is normally distributed and homogeneous, it is continued with hypothesis testing. Hypothesis testing used the independent sample t-test obtained value of  t-count > t-table where t-count = 6,49 while t-table = 2,01 which means that the use of toy props has an effect on the interest in learning mathematics in class VII SMPN I Bola where students’interest in learning mathematics increases. Thus the teacher can use toy props related to the material and can be used in matematics learning so that students’ interest in learning mathematics increases.